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Method of growing a graphene coating or carbon nanotubes on a catalytic substrate

a technology of carbon nanotubes and graphene, which is applied in the direction of catalyst activation/preparation, physical/chemical process catalysts, metal/metal-oxide/metal-hydroxide catalysts, etc., can solve the problems of inability to achieve and the difficulty of achieving continuous monolayer graphene coverage with low defect density

Active Publication Date: 2016-12-29
VALORISATION RECH LLP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for growing a graphene coating or carbon nanotubes on a catalytic substrate using chemical vapor deposition. The method involves exposing the substrate to a carbon-containing gas at a growth temperature, allowing the gas to react with the substrate and produce the desired coating. The ratio of oxidizing species to reducing species in the atmosphere should be about 5×10−6 or less for optimal growth. The method can be carried out in an atmosphere of a reducing species or a gaseous flow of a reducing species. The gases used during the process should be purified to remove oxidizing species. The method can also involve an annealing step and can be carried out under a gaseous atmosphere of a reducing species or an inert species. The graphene coating can be used on a variety of catalytic substrates and the carbon-containing gas can be a hydrocarbon.

Problems solved by technology

According to the literature, the formation of continuous monolayer coverage of graphene on copper requires high temperatures and long growth times, therefore making this process unsuitable for industrial manufacturing.
Indeed, despite substantial efforts, obtaining continuous monolayer graphene coverage with low defect density remains a challenge and can generally only be achieved at high temperatures and after long growth times.
While roll-to-roll approaches are potentially interesting in terms of scalability and manufacturing volume, they still require long growth times and high temperature; thus the associated energy cost remains prohibitive.
Local heating synthesis routes, although much more cost- and time-effective, currently result in lower quality films with microcracks.
However, the resulting processes are still too long and generally fail to enhance the economical viability of the mass production of graphene material.
Thus, the large scale manufacturing of graphene films by CVD has so far been hindered by these constraints.

Method used

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  • Method of growing a graphene coating or carbon nanotubes on a catalytic substrate
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  • Method of growing a graphene coating or carbon nanotubes on a catalytic substrate

Examples

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example 1

Graphene CVD: Interplay Between Growth and Etching on Morphology and Stacking by Hydrogen and Oxidizing Impurities

1. Introduction

[0183]We report herein the results of experiments designed for clarifying the role of H2 and oxidizing impurities during graphene growth from CH4 on copper foils at 500 mTorr pressure and at high temperature (in the 950-1000° C. range). Taking advantage of gas purifiers, we designed a series of experiments to decouple the role of oxidizing impurities, methane, argon, and hydrogen during the growth and post-growth process steps.[0184]We first show that high purity molecular hydrogen does not etch graphene films on copper even at the growth temperature of 950° C.[0185]Further, for extremely low levels of oxidizing impurities, the presence of H2 is not required for growing high quality graphene layers. That is, continuous and uniform graphene films were successfully grown using solely purified CH4 (O2[0186]Under standard conditions (unpurified gases), however...

example 2

Speeding-up Graphene Chemical Vapor Deposition

Introduction

[0234]A careful analysis of the recent literature on LP-CVD of graphene on Cu reveals numerous apparent inconsistencies in terms of optimal growth parameters. In particular, growth duration for CVD from a methane / hydrogen mixture ranges from 5 to 45 min or even higher with no specific reasoning behind it. We recently suggested that oxygen impurities, not hydrogen, are responsible for graphene etching on copper and that there is a competitive action between oxidation and carbon growth during graphene formation in LP-CVD reactor. [S. Choubak, M. Biron, P. L. Levesque, R. Martel, and P. Desjardins, J. Phys. Chem. Lett. 2013, 4, 1100-1103] We show here that the presence of different levels of impurities in the furnace atmosphere and gas feedstock explains the discrepancies in growth recipes from one group to another. In the relative absence of these oxidizing impurities, we hypothesize here and then show that oxidation and etchin...

example 3

Details on the Kinetic Model Presented in Example 2

1) Surface Carbon Production Rate

[0259]The following model has been developed to simulate the effect of oxidizing impurities in the copper catalyzed graphene growth under reducing conditions. The model describes competitive reactions between the surface carbon species formed by the methane activation, inhibitor oxygen adsorbates, and anti-inhibitor hydrogen molecules. The simulation aims to determine the interplay between three main reaction channels:[0260]1) GROWTH: methane dissociation at the copper surface to form Graphene Intermediate Species (GIS) and their reaction to grow graphene;[0261]2) INHIBITION: adsorption and surface reaction of oxidizing impurities with GIS at the copper surface and desorption / elimination via CO gas; and[0262]3) ANTI-INHIBITION: competitive hydrogenation of the oxidizing impurities at the surface of copper and desorption of water gas.

[0263]All the reactions are assumed to occur at the Cu surface. That...

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Abstract

A method of growing a graphene coating or carbon nanotubes on a catalytic substrate by chemical vapor deposition is provided. In the method, the chemical vapor deposition is carried out in an atmosphere in which a ratio Pox / Pred is about 5×10−6 or less, wherein Pox is the partial pressure oxidizing species in the atmosphere and Pred is the partial pressure of reducing species in the atmosphere. A catalytic substrate coated with a graphene coating grown according to this method is also provided.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit, under 35 U.S.C. §119(e), of U.S. provisional application Ser. No. 62 / 183,428, filed on Jun. 23, 2015. All documents above are incorporated herein in their entirety by reference.FIELD OF THE INVENTION[0002]The present invention relates to a method of growing a graphene coating or carbon nanotubes on a catalytic substrate. More specifically, the present invention is concerned with method of growing a graphene coating or carbon nanotubes on a catalytic substrate by chemical vapor deposition of a carbon-containing gas.BACKGROUND OF THE INVENTION[0003]Chemical vapor deposition (CVD) of graphene on copper substrates demonstrates great potential for its large-scale production and its integration in industrial applications. In fact, it is one of the most promising and widely employed methods to produce large graphene sheets of high quality.[0004]Low-pressure chemical vapor deposition (LP-CVD) of graphene films, de...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C01B31/04B01J23/72C23C16/01C01B31/02C23C16/26C23C16/02
CPCC01B31/0453C23C16/26B01J23/72C23C16/01C01B31/0233C23C16/0209C23C16/45557B01J37/06B01J37/08B01J23/745B01J23/75B01J23/755C01B32/162C01B32/186
Inventor CHOUBAK, SAMANLEVESQUE, PIERREGAGNON, PHILIPPEMARTEL, RICHARDDESJARDINS, PATRICK
Owner VALORISATION RECH LLP